Sunbird DOHC turbo build ... open to comments, sugestions

Mr_Efficiency · Post by **Mr_Efficiency** » Fri Mar 23, 2007 5:13 am

I've been poking around this site for a while now and I've finnaly decided to go ahead and start on my build, I am shooting for mid 13's in the 1/4 to beat the fastest guy in my car club (he runs a dodge 2.2 turbo on nitrous at 13.

but thats just a goal not really all that crazy about it but it would be nice, i want it to remain streetable as this is my everyday car as well as autocross car.

The list:
C20GET block
C20GET crank
pistons i was thinking either C20GET (they are forged) with valve cut machined into them or stock C20LET
rods i have 3 options, C20GET, C20LET or toga Hbeam forged rods, undecided
ARP rod bolts
balance rods/pistons
copper head gasket
56mm Throttle body
Daewoo DOHC head (P&P slightly, mostly just a gasket match)
stock cams (probly just get adjustable cam gears)
C20GET intake with daewoo flange
turbo header is being made from scratch
intercooler
BOV
70psi fuel pump (out of a GM truck with the vortec motor)
Adjustable fuel pressure regulator
3bar map
T03 turbo
two stage boost controler
looking at around 7-10 psi street and maybe 17-18psi track if it will take it

Turbo specs:
Compressor housing A/R .42
Exhaust housing A/R .48
Compressor inducer 42mm
Compressor exducer 60mm
Exhaust turbine diameter 48mm

Any sugestions or thoughts? think i can make my goal with this set up? any problems you can see already? what are your opinions on pistons and rods with this kind of set up, I heard the C20GET rods were good for 400hp balanced with ARP rod bolts, what do you guys make of this? also think I would be ok with C20GET pistons? they are forged i just need to machine the valve cuts into them which is not a big deal for me i can do it myself.

thanks

Also I'm doing motor mounts and alot of suspension and tranny work to get it to hook up but i didnt include that in the build list cause its not really engine stuff.

Mr_Efficiency · Post by **Mr_Efficiency** » Fri Mar 23, 2007 5:49 am

Also forgot to mention I was thinking of 48lbs injectors to keep up with fuel, would they be a safe choice?

Nubira2.2 · Post by **Nubira2.2** » Fri Mar 23, 2007 4:07 pm

everything looks good
i would use a hybrid turbo T03/T04

Mr_Efficiency · Post by **Mr_Efficiency** » Sun Mar 25, 2007 2:37 pm

Do you think the turbo i posted above is big enough?, what about piston and rods, what do i have to go with to safley hold this thing together in the bottom end? any guesses as to what this would put out hp wise? just a rough estimate maybe from someone with a similar set up.
thanks

Nubira2.2 · Post by **Nubira2.2** » Sun Mar 25, 2007 5:17 pm

T3 turbo that you mentioned is ok
a friend of mine did 209whp @ 15psi with a turbo like that one in a 1.8L soch engine
with stock internals yes i would go with the T3

but if your are planning
changing pistons and rods
a bigger compressor and wheel yould give you more advantage with the new internals

Mr_Efficiency · Post by **Mr_Efficiency** » Mon Mar 26, 2007 1:24 am

Its just i have that turbo already cause it was cheap and looked decent so i grabed it, figure worse case senario I could just sell it if i dont use it, I'm still undecided on changing pistons and rods, Pistons I'm probly staying with stock cause they are forged, rods i heard if debeamed, polished and shot peened with ARP rod bolts will be good to 400HP, whats it cost to have all that done to rods? or would it be cheaper to just get the toga H beamed forged rods? I'd like to keep stock rods but if i have to i will go with aftermarket.
Also what should i do for headgasket? i was thinking cooper but i've been looking around this site a little more and noticed nobody uses one, what are you guys useing in high boost aplications and how do they hold up?
thanks for the quick replys so far

Post by **PrecisionBoost** » Mon Mar 26, 2007 1:54 am

I would forget the Copper head gasket and go with a Cometic MLS gasket.... I've heard of a few guys using the copper gaskets and there were troubles with sealing the cylinders... especially when the engine was cold.

As well there isn't much room to ring the cylinders (machine a groove in both the block and head and install a stainless ring in combination with a copper gasket)

If your doing all this work I would suggest you get the cylinders bored out to get the correct clearance for new pistons/rings.

Both GsiTurbo and myself did our own debeaming and polishing on a set of C20LET rods (think he sold his.... I still have mine) and shot peening isn't too expensive.

You have to remember that the C20LET rods are not compatible with the stock C20GET pistons...... the LET rod/pistons has a floating pin design where as the GET is a press fit pin.

You might be able to screw around and make them work.... but the local machine shop GSiTurbo uses would not install that combination.... they would not warranty such a combination.

The Toga rods are also for a floating pin design.... so if you want to go with the C20GET pistons you have no choice but to use the C20GET rods and hope they hold.

I personally suggest the combination of Toga rods and the Wiesco forged pistons.

After GsiTurbo's engine came back from the machine shop (all the build are race engines) the owner said he would warranty the engine as long as he kept it under 1000hp... so that says alot about the rods and pistons.

8:1 is too low for the 16V in my opinion..... I personally think 8.5:1 to 8.8:1 is perfect for the kind of power you want to make.

Both the Toga and Wiesco parts can be ordered from IPP (which you probably allready know )

GsiTurbo ended up having to order a slightly thicker Cometic MLS gasket compared to stock to get the right clearance.... I think he mentions the thickness in his buildup

Mr_Efficiency · Post by **Mr_Efficiency** » Mon Mar 26, 2007 2:37 am

thanks, I never mentioned compression tho, i was thinking anywere from 8.5-9:1, do you have any idea as to how the compression would come out with C20GET pistons and the daewoo head?

I think the C20GET bottom end will hold together, if not then o'well, I would have learned the limits of the C20GET and I'll rebuild it and use what you said above cause i know for fact it will hold together, then i could run nitrous and not have to worry, I'm staying away from it with the C20GET bottom end.